Plumb bob reel



July 20 1948. I H. B. NELSON PLUMB-BOB REEL Filed Aug. 2, 1945 FIGI WW HOMER B. NELSON Patented July 20, 1948 UNITED S PAT ENT *OF'FICE BOB REEL Hoiner B. Nelson, UnitedStatcsNav-y Application August 2, 1'945,"Serial*No. 60854-7 1 1Claim. (01.334217) V V (Granted under the at: of "March *3, 1883, as

'1 invention relates to improvements in plumb-bobs and more particularly to cord windmg mechanism 4 contained" within the saidgplumb- This bob.

unbalancing the same.

A further object of this invention is to provide a plumb-bob equipped with a cord winding mechanism, as set out above, that can be locked to hold the cord at any length desired, Without unbalancing the said plumb-bob.

Other objects and advantages of this invention will become apparent as the discussion proceeds and is considered in connection with the accompanying claims and drawings wherein like characters of reference designate like parts through- .out, and wherein:

Fig. I shows a vertical cross sectional view of the plumb-bob involved in this invention;

Fig. II shows a horizontal cross sectional view of the plumb-bob embodied in this invention taken on the line II-II of Fig. I.

Referring now to the drawings, wherein for the purpose of illustration, is shown a preferred embodiment of this invention, the numeral 5 designates a base or lower housing of a conventional cylindrical plumb-bob having a hollow chamber 6 symmetrically disposed about the vertical axis of said plumb-bob having a cap or upper housing 7 threadably ailixed to the base at 8. Slidably carried within the tubular chamber 6 is a spindle 9, having a tubular center member l0 threaded on the upper end at H. A threaded insert l2 having a shoulder I3 is threadably affixed to the upper end H of the tubular member i0, and urges the spindle up or down in the said chamber when turned.

Rotatably carried upon the spindle 9 is a spool or drum I4 adapted to receive a string or cord 15, as shown. The upper portion of the said spool l4 rigidly carries, upon its upper portion, a cylinder [6 adapted to house two equally balanced torsion springs I 1 and I8, balanced 180 apart so that the weight distribution of one spring balances that of the other spring at every position of tension, as shown in Fig. II, separated from each other by a plate 32. One spring I1 is affixed at its outer terminus by a pin or rivet [9 to the spool l4 and the inside terminus of the same is afiixed to the upper portion of the center member 10 by pins or rivets 20. The other spring Hlfis aifixedby 1-ivets"orpins -2l 'at-itsouter 'tei'minuato the said spool "or "diametrically opposite from the. rivet l9by a pin'or rivet/21 and the inn'erterminus of this-second spring I 8 is afiixedto the centerrnember rill, 'I80 "from -or dimetrically opposite to the'inner term'inus'ofth'e first-mentioned spring, by a pin or rivet 22.

In assembling the above mechanism the spool and spring are assembled on to the spindle and the insert I2 is threaded on to the upper end ll of the spindle 9, as shown. This assembly is then inserted into the upper half of the plumbbob and the insert [2 is fitted into the shoulder recess 23 provided therein, as shown. A shoulder thumb nut 24 is threaded on to the upper end of the said insert to hold the spindle and spool in place. A set screw 25 prevents the thumb nut 24 from becoming loose from the insert l2. Two elongated slots 26 cut in the base of the spindle and disposed 180 set screws 21 to prevent rotation of the said spindle, but allow lateral movement of the entire assembly. The cylinder I6 is provided with a raised rim 28 extending slightly above the springs l1 and I3, and is machined to engage against the corresponding under-surface of the cap 1. When the spindle 9 is urged upward by turning the thumb-nut 24 the spindle and drum are urged upward and the rim 28 brakes against the under side of the cap 1 and locks the spool and cylinder in place. The said string [5 is wound on the spool It and then run downward from the said spool through a channel 29 provided in the base of the spindle. A second channel 33 of equal size to the channel 29 is provided in the base of the spindle, 180 from the channel 29 to balance the same, as shown. The string or cord then passes under the spindle 9 up through the tubular member l0 and out the plumb-bob through a passage 30 providedin the center of the thumb screw and insert. The string is provided with a hook or ring 3| to permit suspension of the plumb-bob from a stationary object.

In operation, the balanced springs urged the drum to wind the string on the spool. The string is withdrawn from the spool to any length desired and the thumb screw is turned to draw the spindle and drum upward thereby locking the spool in place, thus holding the string at the desired length.

It is to be noted that the features of the plumbbob embodied in this invention are such that the plumb-bob is balanced about its vertical axis regardless of any variation in the length of the string or in looking or unlocking the drum,

apart, as shown, receive stub.

It is to be understood that the form of the invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claim.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What I claim is:

In a plumb-bob having a chamber therein symmetrically disposed about the vertical axis within said chamber comprising a tubular spindle slidably mounted vertically in the said chamber, a spool rotatably mounted on the said spindle carrying a string winding means on one end and a spring carrying drum on the other end having a rim cooperating with the inner walls of said chamber, a string wound on the said drum, a

pair of torsion springs balancing each other in weight distribution in all positions of tension and 2 actuating the rotational movement of said spool and symmetrically mounted about the said vertical axis of said plumb-bob within the said drum, each spring being connected at one end to the said spool and at the other end to the said 5 spindle, the spool connections being diametrically disposed with respect to each other and the spindle connections being diametrically disposed with respect to each other, anda thumb screw threadably afiixed to the said tubular spindle 10 adapted to urge the said spindle upward to bring the rim oi said spring drum into engagement with the said chamber wall to brake the said spool and hold the string at any length desired.

15 I HOMERB. NELSON. of said plumb-bob, a string winding mechanism REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 279,316 Avery June 12, 1883 748,132 Wolf Dec. 29, 1903 5 1,076,569 Gambllee Oct. 21, 1913 Morris July 21, 1912 

